This invention relates to a disposable diaper for absorption and containment of urine and other body exudates.
Japanese Patent Publication Gazette (Kokoku) No. Hei3-80502 discloses a disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet, a liquid-absorbent core disposed between these two sheets and a pair of flexible barrier flaps which are stretchable and contractable under action of elastic members. Each of the barrier flaps comprises a branched portion extending upward from an inner side of the diaper and a sealing surface zone extending transversely from a top of the branched portion. The sealing surface zone consists of a first overhang extending inward and a second overhang extending outward respectively from the top of the branched portion. In this known diaper, normally the first overhang is elastically placed against a wearer""s inguinal region and forms a pocket adapted to be opened inwardly so that this pocket may receive and contain loose passage and/or urine. The second overhang is elastically pressed around the wearer""s leg to fasten the diaper around the wearer""s leg and improves a leakage proof effect for body exudates.
The invention described in the Publication Gazette teaches that it is preferred to form the flaps at least partially by the material which has a high flexibility, breathability and liquid-impermeability. As examples of such material, a nonwoven fabric, an apertured plastic film and a laminate of these two materials are described, but none of further specific examples is described. Practically, the spun bond nonwoven fabric of polypropylene fibers has often been adopted as such nonwoven fabric.
From a viewpoint that the second overhang should be tightly pressed against the wearer""s leg, the elastic members of a relatively high tensional stress are preferably used for the second overhang. On the other hand, the first overhang functions as a barrier flap and therefore it is required for the elastic members used in this overhang merely to contract sufficiently to rise the barrier flap and thereby to open the pocket. Also for the purpose of avoiding any apprehension that the first overhand might uncomfortably compress the wearer""s skin, it is preferred to use the elastic members presenting a relatively low elongation stress in this first overhang.
In view of the problem as has been described above, it is an object of the invention to provide a disposable diaper having the barrier flaps which are sufficiently soft to allow the elastic members to smoothly contract in order that the elastic members of an elongation stress as low as possible can be used.
According to the invention, there is provided a disposable diaper having a basic diaper structure including a liquid-pervious topsheet, a liquid-impervious backsheet, a liquid-absorbent core disposed between the topsheet and the backsheet; a pair of side flaps extending outward along transversely opposite side edges of the absorbent core, and a pair of barrier flaps formed on an inner side of the diaper so that the barrier flaps rise on the inner side of the diaper, wherein:
each of the barrier flaps is made of a nonwoven fabric and includes a proximal end positioned on the inner side of the diaper, a risable wall extending upward from the proximal end, a sealing surface zone formed on a top of the risable wall so as to extend transversely of the diaper and a plurality of elastic members extending longitudinally of the barrier flap and secured under tension to the sealing surface zone; and the nonwoven fabric forming the barrier flap is a spun bond nonwoven fabric made of wich/sleeve type conjugated fibers including a sleeve component of polyethylene and a wick component of thermoplastic synthetic resin other than polyethylene, and the spun bond nonwoven fabric has a fineness of 1xcx9c3 d, a relative hardness of 40xcx9c50 mm in an MD-direction and 20xcx9c37 mm in a CD-direction as measured by the cantilever method and a basis weight of 15xcx9c30 g/m2.
According to one embodiment of this invention, the wick of the conjugated fibers is made of thermoplastic synthetic resin selected from polypropylene and polyester.
According to another embodiment of this invention, the MD-direction of the nonwoven fabric coincides with a longitudinal direction of the barrier flaps.